Dr. Mehmet Oz answered:
Hair is great for running your fingers through and growing make-a-statement goatees, but having hair was once far more purposeful than simply serving as bodily ornamentation. For early humans, hair kept them warm, protected them from cuts and scrapes, provided camouflage, and even served as a nice handhold for the young. They were much hairier than modern humans, and the reason that we lost a lot of body hair over time isn't because we invented heaters and parkas. More likely, our ancestors started hunting in hot, tropical areas - and bare skin adds to the efficiency of our cooling system. The reason why we kept the tuft at the top? Many experts agree that it had to do with a mating ritual that went a little something like this: The male with the most impressive hair - or he who could make it look that way - frightened away his rivals, got his girl, and fathered the next generation. Hence, head hair played a major role in obtaining a partner and successfully producing offspring.
Today, our hair still performs many useful functions, in addition to keeping barbers employed. The hair on our scalps protects us against the sun, and our eyelashes act as our first defense against bugs, dust, and other irritating objects. In the phase of human development when our ancestors had lost their full-body follicular coverage but clothes were still as scarce as skyscrapers, the hair in our nether regions camouflaged our reproductive parts from generation-threatening spears. And by lining our armpits - we docs call this the axilla - and groins, our dry hair actually acts as a lubricant, allowing our arms and legs to move without chafing.
Also, both then and now, our body hair serves as a protector against malaria. The Anopheles mosquito - a low-flying bug that likes the legs - hates hair, in part because hair warns its victim to start swatting. While their bite is painless, our hair signals the presence of mosquitoes before they bite (it's why kids are at greater risk - they have less hair on their legs). That's most likely the original purpose of hair: it served as an early warning system of bodily threats. We seem to ignore the armor function of our hair today, removing it every chance we get, except on our heads and eyes.Find out more about this book: YOU: Being Beautiful: The Owner's Manual to Inner and Outer BeautyHair is great for running your fingers through and growing make-a-statement goatees, but having hair was once far more purposeful than simply serving as bodily ornamentation. For early humans, hair kept them warm, protected them from cuts and... More